US 5,180,475 A · System and method for controlling electroosmotic flow

Abstract

A system and method for controlling the rate of electroosmotic flow in capillary electrophoresis. A first high voltage power supply is electrically connected to the inlet end of a capillary tube, while a second high voltage power supply is connected at an outlet end. The potential difference across the capillary tube is therefore the difference between the high voltages. Electroosmotic flow can be controlled by varying the two high voltages correspondingly to maintain the same potential difference but to achieve a different voltage offset relative to ground. Optionally, the voltage offset may be varied during electrophoresis analysis to slow migration during periods in which constituents are closely spaced and to speed migration when constituents are sufficiently spaced apart. A conductive capillary tube coating which is preferably grounded defines an external control area for electroosmotic flow. A detector is located downstream of the external control area, so that the coating is a unitary layer.

Claims15

Dependent claims

A method of controlling the rate of electroosmotic flow of a sample solution comprising,

providing an electrophoresis apparatus having a flow region,
inducing an electroosmotic flow of a solution within said flow region,
electrophoretically separating constituents of said solution, including applying a first voltage level to a first end of said flow region and applying a second voltage level to a second end of said flow region,
changing the rate of electroosmotic flow along said flow region during said step of electrophoretically separating constituents by adjusting the voltage levels at each of said first and second ends relative to ground, thereby providing a third voltage level to said first end and providing a fourth voltage level to said second end, the potential difference between said first and second voltage levels being substantially equal to the potential difference between said third and fourth voltage levels, and
continuing said step of electrophoretically separating said constituents at said changed rate of electroosmotic flow.

2 more elements

A method of controlling the rate of electroosmotic flow of a sample solution comprising,

providing a capillary tube having first and second ends and having an inner layer defining an inside diameter for the flow of a sample solution there along, said capillary tube having at least one outer layer including a conductive coating along a region of said capillary tube spaced apart from said first and second ends,
electrically connecting a first high voltage supply to said first end,
electrically connecting a second high voltage supply to said second end,
electrically grounding said conductive coating on said capillary tube,
selecting a desired axial potential gradient between said first and second ends of said capillary tube,
selecting a potential difference between said first and second high voltage supplies to achieve said desired axial potential gradient,
selecting magnitudes, relative to ground, of voltages for said first and second high voltage supplies to achieve said potential difference and to generate a desired radially-directed electrical field for spatial separation of constituents in a sample solution, said selecting of magnitudes being a selecting of voltages less than or greater than ground,
applying said selected magnitudes of voltages to said first and second ends, and
detecting said separation of constituents prior to exit of said constituents from said capillary tube.

6 more elements

Dependencies are inferred from the claim text.

System and method for controlling electroosmotic flow

Life of this patent

System and method for controlling electroosmotic flow

Life of this patent

Abstract

Claims15